Rotor Parts Research Articles

Space-time shape optimization of rotating electric machines

This paper is devoted to the shape optimization of the internal structure of an electric motor, and more precisely of the arrangement of air and ferromagnetic material inside the rotor part with the aim to increase the torque of the machine. The governing physical problem is the time-dependent, nonlinear magneto-quasi-static version of Maxwell’s equations. This multiphase problem can be reformulated on a 2D section of the real cylindrical 3D configuration; however, due to the rotation of the machine, the geometry of the various material phases at play (the ferromagnetic material, the permanent magnets, air, etc.) undergoes a prescribed motion over the considered time period. This original setting raises a number of issues. From the theoretical viewpoint, we prove the well-posedness of this unusual nonlinear evolution problem featuring a moving geometry. We then calculate the shape derivative of a performance criterion depending on the shape of the ferromagnetic phase via the corresponding magneto-quasi-static potential. Our numerical framework to address this problem is based on a shape gradient algorithm. The nonlinear time periodic evolution problems for the magneto-quasi-static potential is solved in the time domain, with a Newton–Raphson method. The discretization features a space-time finite element method, applied on a precise, meshed representation of the space-time region of interest, which encloses a body-fitted representation of the various material phases of the motor at all the considered stages of the time period. After appraising the efficiency of our numerical framework on an academic problem, we present a quite realistic example of optimal design of the ferromagnetic phase of the rotor of an electric machine.

Diagnosis of ring cracks on the shafting line of a turbo unit

Due to the growing number of accidents associated with damage to turbine unit shafts, there is a pressing need to diagnose the occurrence and growth of ring cracks not only during planned repair work on the turbine unit, but also directly during its operation to prevent emergency failures and costly repairs of the machine. Ring cracks that develop in the shafting do not lead to an increase in the level of vibration of the rotor or its support bearings and, therefore, cannot be detected by standard operational vibrodiagnostic systems. In this paper we propose a method that allows for the diagnosis of the occurrence and growth of ring cracks on the turbine unit shafting. The method is based on the influence of the depth of an annular crack in the shaft on the angle of its twist during machine operation. The presence of this relationship is determined through calculations based on the parameters of the experimental low-pressure turbine 2, used by the Central Boiler and Turbine Institute named after I. I. Polzunov. The practical implementation of this method is proposed to be carried out using the twist angle determination technique developed based on the discrete-phase method by means of measuring and analyzing changes in the shaft twist angle during turbine unit operation. Technically, this is achieved by employing a system consisting of inductors and sensors fixed to the stator and rotor parts of the machine. The proposed method can be used as a supplement to existing methods of operational control of the actual condition of the shafting, as well as, in the future, to assess the actual efficiency of the turbomachinery cylinders.

Investigations into rubbing wear behavior of honeycomb land against labyrinth fin with periodic-cell model

The periodic-cell model was proposed to simulate the successive contacts between the labyrinth fin and multiple honeycomb cells. With the experimental data, the finite-element-analysis (FEA) method with the periodic-cell model was validated. The effects of incursion parameters (i.e. incursion depth, incursion rate and sliding velocity) on the contact force, frictional temperature, material loss, and worn geometry of the honeycomb seal during the incursion process were studied. With the predicted worn geometry, the sealing performance degradation in the honeycomb seal was analyzed. The results showed that the proposed periodic-cell model has an excellent accuracy in predicting the wear behavior of honeycomb seal in rubbing events. The contact force between the honeycomb liner and labyrinth fin is pronounced especially at low sliding velocity and high incursion rate conditions, which increases the possibility of wear damage in the rotor part. At low sliding velocity and low incursion rate conditions, the frictional heat transferring to rotor part is increased, which increases the thermal stress near the contact region of the rotor part. As the clearance gap of honeycomb seal increases from 0.6 mm to 0.9 mm in the rubbing event, the leakage rate is increased by about 12%, and the carry-over effects downstream of the worn cells are increased.

Aqueous Supramolecular Transformations of Motor Bola-Amphiphiles at Multiple Length-Scale.

Molecular motor amphiphiles have already been widely attempted for dynamic nanosystems across multiple length-scale for developments of small functional materials, including controlling macroscopic foam properties, amplifying motion as artificial molecular muscles, and serving as extracellular matrix mimicking cell scaffolds. However, limiting examples of bola-type molecular motor amphiphiles are considered for constructing macroscopic biomaterials. Herein, this work presents the designed two second generation molecular motor amphiphiles, motor bola-amphiphiles (MBAs). Aside from the photoinduced motor rotation of MBAs achieved in both organic and aqueous media, the rate of recovering thermal helix inversion step can be controlled by the rotor part with different steric hindrances. Dynamic assembled structures of MBAs are observed under (cryo)-transmission electron microscopy (TEM). This dynamicity assists MBAs in further assembling as macroscopic soft scaffolds by applying a shear-flow method. Upon photoirradiation, the phototropic bending function of MBA scaffolds is observed, demonstrating the amplification of molecular motion into macroscopic phototropic bending functions at the macroscopic length-scale. Since MBAs are confirmed with low cytotoxicity, human bone marrow-derived mesenchymal stem cells (hBM-MSCs) can grow on the surface of MBA scaffolds. These results clearly demonstrate the concept of designing MBAs for developing photoresponsive dynamic functional materials to create new-generation soft robotic systems and cell-material interfaces.

Influence of choosing materials on 6/4 switched reluctance motor performance

The Switched Reluctance Motor (SRM) is used in many industrial applications that require high torque due to its ability to achieve high and efficient performance, simplicity, low material costs and ease of design. This motor functions on the principle of generating motion by attracting and repulsing magnetic cores. The SRM is characterized by the efficient use of energy in applications that require rapid changes in speed and has a higher resistance to shocks and vibrations. Among the essential factors that affect the performance of the SRM motors are the embrace of poles stator and rotor, dimensions, the size of the motor, the shapes of rotor geometry and the number of stator and rotor poles. This paper aims to study the effect of material selection on improving the SRM performance. First, we created a basic design of the SRM with appropriate characteristics to obtain the best operation conditions of high speed and torque. Then, we applied different materials and compared the obtained results using the ANSYS RMxprt tool. We focused on studying the effect of selecting materials in the rotor and stator parts on the SRM 6/4 performance through the efficiency, total losses, speed and rated torque. After comparing and analyzing the basic results, a two-dimensional model of the SRM was created using the ANSYS Maxwell 2D tool to evaluate the motor’s performance. The analysis includes the curves of torque, speed, current, flux linkages and voltage, in addition to the variation of flux lines and magnetic flux density. The results were analyzed using the finite element method (FEM), which is characterized by speed and accuracy in electromagnetic analysis and various data.

Research of strength parameters and dynamic characteristics of rotor parts of a promising small sized GTE

The presented work demonstrates a study devoted to assessing the strength characteristics of the rotor elements of a promising small-sized gas turbine engine. The main feature is that the analysis of the stress-strain state of the engine rotor is carried out taking into account vibrations and resonant frequencies. In turn, the assessment of the dynamic characteristics of the rotor elements was carried out taking into account the conditions of their mutual contact. The research materials presented in this article will serve for further iterations of engine design.

Метод чисельного визначення динамічних характеристик лопаті повітряного гвинта з композиційного матеріалу

The subject matter of this article is the dynamic characteristics of a composite propeller blade. Determination of the modes and frequencies of natural vibrations is necessary to predict the dangerous resonance modes of aircraft engines and to identify the most stressed local zones of the blade surface. The goal of this study is to develop a verified method for determining the dynamic characteristics of composite rotor parts of aircraft engines based on the known properties of the structural components of the composite material. A general mathematical statement of the problem of elasticity theory for the analysis of the dynamic characteristics of composite structures is described. A complete system of equations that describes the mechanical state of the body within the framework of the continuum mechanics approach was developed. Geometric modeling of the propeller blades was performed. Modeling and numerical investigation of the natural frequencies and mode shapes of the propeller blade were performed using the finite element method using the ANSYS software package. Based on the results of numerical research of the stressed and deformed state of the propeller blade, the first five natural vibration frequencies and the distribution of the local stress field were determined. The most stressed local zones on the blade surface were determined for each form of natural vibration. The propeller blade model was verified using an experimental study of the first five forms and frequencies of natural blade vibrations. The eigenfrequencies of the blade vibration were experimentally determined using the method of free (natural) vibrations. The resonance method was used to experimentally determine the resonant frequencies and vibration modes of the blade. The distribution of the blade deformation field was investigated using the strain gauge method. The highest error in the verification of numerical and experimental research is 4.11% for the fourth vibration frequency. Conclusions. The scientific novelty of the results obtained is that the effective elastic properties of the composite material for calculations should be determined using the procedure of numerical homogenisation of composite materials of different reinforcement structures by the properties of the matrix and fibers. The method does not require experimental determination of the effective elastic constants for the layers of blade components of different weave architecture patterns.

Design and Non-Linearity Optimization of a Vertical Brushless Electric Power Steering Angle Sensor.

This paper presents the design and the non-linearity optimization of a new vertical non-contact angle sensor based on the electromagnetic induction principle. The proposed sensor consists of a stator part (with one solenoidal excitation coil and three sinusoidal receiver coils) and a rotor part (with six rectangular metal sheets). The receiver coil was designed based on the differential principle, which eliminates the effect of the excitation coil on the induced voltage of the receiver coil, and essentially decouples the excitation field from the eddy current field. Moreover, the induced voltages in the three receiver coils are three-phase sinusoidal signals with a phase difference of 10°, which are linearized by CLARK transformation. To minimize the sensor non-linearity, the Plackett-Burman technique was used, which identified the stator radius and the rotor blade thickness as the key factors affecting the sensor linearity. Then, the particle swarm algorithm with decreasing inertia weights was utilized to optimize the sensor linearity. A sensor prototype was made and tested in the laboratory, where the experimental results showed that the sensor non-linearity was only 0.648% and 0.645% in the clockwise and counterclockwise directions, respectively. Notably, the non-linearity of the sensor was less than -0.696% at different speeds.

Analysis of longitudinal-vertical coupling vibration of four hub motors driven electric vehicle under unsteady condition

The influence of hub motor unbalanced magnetic force (UMF) on the vibration of electric vehicle under steady state conditions has been known, but under unsteady conditions, the hub motor UMF will change with the vehicle operation condition, and there would exist complex coupling vibration for the hub motors driven electric vehicle. Here, the longitudinal-vertical coupling dynamics of the four hub motors driven electric vehicle under unsteady condition is studied. Integrating the motor electromagnetic excitation and electric vehicle dynamics, a longitudinal-vertical coupling dynamics model of the four hub motors driven electric vehicle is established. Based on the variable switching frequency field-oriented control model, analytical model of the UMFs acting on the motor stator and rotor parts under unsteady condition are developed. For model validation, a four hub motors driven electric vehicle has been tested, the accuracy of the longitudinal-vertical coupling dynamics model established in this paper was verified. Then, longitudinal-vertical coupling vibration characteristics of the four hub motors driven electric vehicle under road excitation and coupling excitation are analyzed. The results show that the longitudinal and vertical movement of the four hub motors driven electric vehicle is coupled by hub motor. In addition, under unsteady condition, the motor UMFs will cause vertical vibration of the electric vehicle body and hub motor stator, the vibration shows order characteristics including low order harmonic hfc and inverter switching frequency sideband harmonic k1 fs±k2 fc ( fc = pn/60, fs is inverter switching frequency, k1 and k2 are positive integers, p is the number of pole pairs and n is motor speed.). The motor electromagnetic torque will cause longitudinal vibration of the electric vehicle body, the vibration shows order characteristics including harmonics fs±3 fc and 2 fs. The main harmonic of vehicle body pitch angle acceleration is 2 fs.

Investigation of the Formation of Structure and Properties in a Billet Made of Heat-Resistant Nickel Alloy EP741NP, Obtained by Hot Isostatic Pressing Technology

It is known that the technology of hot isostatic pressing (HIP) can reduce the residual porosity and increase the level of physical and mechanical characteristics of products obtained by powder metallurgy methods. In modern aircraft and rocket engineering, heat-resistant heterophase nickel alloys are used, which are obtained with the use of granular metallurgy. This material is indispensable in the creation of disks of gas turbine engines (GTE), which are part of the turbine rotor and serve to install the blades. Obtaining a nonporous product made of EP741NP alloy using the HIP technology will increase the service life of the turbine disks, which is an urgent task at the present time. The aim of the work is to study the structure and physical and mechanical properties of a billet made of heat-resistant nickel alloy EP741NP obtained by the HIP method at a temperature of 1150 °C. The starting material for the preparation of the workpiece is a metal powder EP741NP, obtained by gas atomization and having a fractional composition of 20...50 microns. It is shown that the HIP process at a temperature of 1150 °C makes it possible to obtain an optimal combination of physical and mechanical properties. Based on the obtained images of powder particles and the microstructure of the work piece, the shape of the particles of the powder under study, the main category of powder granularity was determined and digital porosity analysis of the workpiece under study was performed in the Thixomet Pro software package. The changes in density and hardness along the section of the work piece were also evaluated. It has been established that at a temperature of HIP 1150 °, the average porosity is insignificant and is 0.1 %, however, as we move away from the edge of the workpiece to its center, there is an increase in the content of pores, the size of which lies in the range of 1...20 microns. It is shown that during the technological process of HIP, an arched effect is observed, the consequence of which are overestimated characteristics of microhardness and density at the edge of the work piece.

Optimizing circumferential assembly angle of rotor parts connected by curvic couplings based on acquired tooth surface error data

Due to the excellent self-centering and load-carrying capability, curvic couplings have been widely used in advanced aero-engine rotors. However, curvic tooth surface errors lead to poor assembly precision. Traditional physical-master-gauge-based indirect tooth surface error measurement and circumferential assembly angle optimization methods have the disadvantages of high cost and weak generality. The unknown tooth surface fitting mechanism is a big barrier to assembly precision prediction and improvement. Therefore, this work puts forward a data-driven assembly simulation and optimization approach for aero-engine rotors connected by curvic couplings. The origin of curvic tooth surface error is deeply investigated. Using 5-axis sweep scan method, a large amount of high-precision curvic tooth surface data are acquired efficiently. Based on geometric models of parts, the fitting mechanism of curvic couplings is uncovered for assembly precision simulation and prediction. A circumferential assembly angle optimization model is developed to decrease axial and radial assembly runouts. Experimental results show that the assembly precision can be predicted accurately and improved dramatically. By uncovering the essential principle of the assembly precision formation and proposing circumferential assembly angle optimization model, this work is meaningful for assembly quality, efficiency and economy improvement of multistage aero-engine rotors connected by curvic couplings.

A case study on the failure analysis of 1 hp house hold electrical submersible pump in Prayagraj India

This paper deals with the failure analysis of a 1 HP household electrical submersible pump in Prayagraj city. The city is surrounded by two rivers i.e. the Ganga and the Yamuna. Therefore, domestic submersible pumps are widely used in the region. Hard water and sand particles cause various problems with the pump. The submersible pump consists of a pump section and a motor section. The failure analysis of the motor section consists of failure of the rotor, stator, cable and other parts. Similarly, the pump section consists of failure of the impeller, diffuser and other parts. Prevention methods for all failed components have also been discussed in this paper. The failure of a submersible pump can be summarized into three major categories i.e. mechanical failure (breakage, corrosion, dislocation and leakage), electrical failure (cable failure, motor failure, and connection severances) and operational failure (high temperature, high pressure and multiphase flow).

Determination of Mechanical Properties for Laser Welded Turbine Rotor Assemblies for Automotive Turbocharger Applications

To meet the demands of higher speeds, higher power density and the ability to adapt to harsh operating environments over a long period of time, structural designers use various materials to fabricate rotor parts for turbine assemblies. This introduces high requirements for stable rotation and rotor life. It is therefore important to analyse and determine the mechanical properties for a turbine rotor taking into account the manufacturing process. This paper focuses on laboratory mechanical testing for determination and analysis of turbine components consisting of a rotor, from 42CrMo4 (DIN EN 10083-3) and a turbine, made from Inconel 713C in laser welded assembly. The tests carried out consists of tensile testing for the turbine – rotor assembly, microhardness measurements, macro and microscopic examinations of the welded joint. The obtained results stand as a validation for the welding process technology used for this type of application ensuring the superior mechanical characteristics required for operation in harsh enviornments.

Experimental and Numerical Investigation on Finned Vortex Reducer in a Rotating Cavity with a Radial Inflow

In aero-engines, a secondary air system is used to cool the rotor discs and seal cavities between rotor and stator parts. The pressure loss caused by bleed air can be effectively reduced by setting the finned vortex reducer. Thus, the bleed system design can be optimized by researching the flow structure and pressure loss of each section in the cavity with a finned vortex reducer. In this study, the influence of different installation positions of a finned vortex reducer on the pressure loss characteristics was investigated through experimental and numerical simulation methods, focusing on the radial inflow of the secondary air system. The results indicate that the inlet and outlet positions of the fins affect the flow structure in the cavity. The aerodynamic parameters (rotational Reynolds number ReΦ and mass flow rate coefficient Cw), together with the inlet and outlet radii of the fins, influence the pressure loss in the cavity. Considering the swirl ratio β constrained by the fins, a pressure loss model was established, which showed good agreement with the experimentally measured pressure loss. This model reflects the impact of the inlet and outlet positions of the fins on the pressure loss characteristics.

Experimental Study on the Vibration Reduction Performance of the Spindle Rotor of a Rubbing Machine Based on Aluminium Foam Material

Larger vibration and noise often exist in agricultural machinery due to the harsh working environment and high power. The rubbing machine is one of the indispensable pieces of equipment in the agriculture and livestock industry, and it is affected by the vibration of large constraints on its promotion and use. To reduce the vibration of the rubbing machine, the vibration characteristics of the spindle rotor were first analysed by modal simulation, thus determining the larger contributions to the spindle rotor vibration. Second, aluminium foam material was installed in the large deformation part of the spindle rotor. Its vibration reduction and energy absorption characteristics were used to optimise the vibration reduction design by increasing the damping. Third, a steel ball impact test was conducted to analyse the vibration characteristics of the optimised spindle rotor. The results show that the maximum impact accelerations were reduced by 28.4% and 64.75% in the axial and radial directions, respectively, and the impact energies were reduced by 67.3% and 90.65% in the axial and radial directions within 2 s of impact collision, respectively, indicating that the optimised spindle rotor damping increased significantly. In addition, the vibration reduction effect of the optimised rubbing machine was verified by a bench test. By measuring the change degree of the static component of the spindle rotor vibration, the axial, radial, and vertical vibrations of the spindle rotor were improved by 5.78%, 10.32%, and 23.96%, respectively. Therefore, optimising the spindle rotor with aluminium foam material can reduce the vibration generated during the impact of the material on the spindle rotor. The rubbing machine’s vibration, damping, and energy absorption were also realised in real working conditions.

Analysis and Experiment of a Dual Stator/Rotor PM and Winding Flux Modulated PM Machine

In this article, a high torque density flux modulated permanent magnet machine topology with dual permanent magnets and dual armature windings (DMDA-FMPM) is proposed. The most notable feature of DMDA-FMPM is that both stator and rotor parts consist of PMs and armature windings so that a single air gap and a simple structure are kept. Moreover, both the PMs can interact with both the windings to produce four torque components, and the output torque on the shaft is the superposition of these four torque components. Consequently, extremely high torque is expected. This paper firstly introduces the topology and main drive circuit of DMDA-FMPMs. Then the basic operation principle and slot/pole combination equation are illustrated, taking the proposed topology as an example. Afterward, the electromagnetic performance, including flux line distribution, flux density, back electromotive force (EMF), torque quality, and power factor, is analyzed by finite element analysis (FEA). Besides, the fault-tolerance of windings failure and PM demagnetization is discussed. A prototype is designed and tested to verify the proposed DMDA-FMPM. The experimental results match well with the FEA and theoretical analysis. DMDA-FMPM has excellent torque performance and fault-tolerant capability. Finally, the possible applications, operating modes, advantages, and drawbacks are discussed comprehensively.

Structural and Functional Diversity of Two ATP-Driven Plant Proton Pumps.

Two ATP-dependent proton pumps function in plant cells. Plasma membrane H+-ATPase (PM H+-ATPase) transfers protons from the cytoplasm to the apoplast, while vacuolar H+-ATPase (V-ATPase), located in tonoplasts and other endomembranes, is responsible for proton pumping into the organelle lumen. Both enzymes belong to two different families of proteins and, therefore, differ significantly in their structure and mechanism of action. The plasma membrane H+-ATPase is a member of the P-ATPases that undergo conformational changes, associated with two distinct E1 and E2 states, and autophosphorylation during the catalytic cycle. The vacuolar H+-ATPase represents rotary enzymes functioning as a molecular motor. The plant V-ATPase consists of thirteen different subunits organized into two subcomplexes, the peripheral V1 and the membrane-embedded V0, in which the stator and rotor parts have been distinguished. In contrast, the plant plasma membrane proton pump is a functional single polypeptide chain. However, when the enzyme is active, it transforms into a large twelve-protein complex of six H+-ATPase molecules and six 14-3-3 proteins. Despite these differences, both proton pumps can be regulated by the same mechanisms (such as reversible phosphorylation) and, in some processes, such as cytosolic pH regulation, may act in a coordinated way.

Design optimization of Spoke IPM motor for improving efficiency using PSO and Rao-1 algorithm based FEA

The rate of demand for permanent magnet synchronous motors (PMSMs) in all types of applications is elevated day by day. Many topologies of PMSM have been developed and utilized in different sectors. Many software are available for primary analysis of motors, which have an inbuilt finite element solver. The study presented in the paper aims to optimize a spoke shape interior permanent magnet synchronous motors (IPMSMs) design parameters using particle swarm optimization technique (PSO), and Rao-1 algorithm. In this research, a 4 pole 24 slots spoke shape IPMSM motor is considered to optimize its parameters such as outer, inner stator diameter, rotor outer diameter, the height of magnet, stator tooth width, and the base width of the slot. Results obtained, and the effectiveness of optimization are validated by comparing with the results reported in the literature. Efficiency, torque, magnetic field, and other electromagnetic parameters are calculated and reported for the optimized IPMSM parameters. For improving the efficiency of IPMSM, an analysis of its different design factors is focused. In this study, efficiency improvement is achieved by optimizing stator slot featuring, and rotor parts designing. The corresponding results are reported. The complete operational analysis has been conducted in ANSYS Maxwell and MATLAB environment. Here total excitation of the motor highly depends on the magnetic material used in the rotor part of the motor.

ON THE SELF-STARTING COMPARATIVE PERFORMANCE EVALUATION OF DARRIEUS AND HYBRID HYDROKINETIC ROTOR

Darrieus rotor is a promising technology for hydrokinetic and wind energy harvesting applications. However, the Darrieus rotor suffers from the problem of poor starting performance. The present research highlights solutions to improve the poor starting performance of the Darrieus rotor by introducing the hybrid rotor. Further, a comparative performance evaluation of conventional vertical axis Darrieus and hybrid rotors has been investigated numerically. The most widely used S-series S-1046 hydrofoil has been utilized by hybrid and Darrieus rotors. Further, two semicircular blades are used for the Savonius part of the hybrid rotor. The size of the Savonius part is optimized to obtain maximum performance from the hybrid rotor. Analyzing the flow field distributions across the turbine vicinity has highlighted various possible reasons. The study results have demonstrated that the hybrid rotor yields an exceptional increment of about 159.41% in the torque coefficient under low tip speed ratio (TSR) regimes (during initial starting) compared to the Darrieus rotor. However, due to the Savonius rotor's presence, the hybrid rotor's maximum power coefficient is reduced slightly compared to the maximum operating point of the Darrieus rotor. Further, the hybrid rotor yields a wider operating range than the single maximum operating point by the Darrieus rotor. The present investigations will assist the designers in selecting the site-specific hydrokinetic technology suitable for efficient and optimum use of hydrokinetic potential.

The annulling of the sudden appearance of an unbalance in rotary machines by using active magnetic bearings

The application of magnetic bearings has become more frequent during the last 20 years and represents a significant aspect of improvements in the construction of machines with rotary motion. With the advancement of technology, the number of applications in which magnetic bearings have found their application is increasing. In this paper, it is shown how the effect of magnetic forces can annul the negative influence of unbalance, which suddenly appeared in a rotor supported in active magnetic bearings. Such cases may occur in operation due to breakage and rotor parts falling off (e.g., fan blades), which will lead to a sudden change in the mass balance of the rotor system and dislocation of the centre of mass in relation to the geometric centre of the rotor. In the paper, a mathematical model of the dynamic behaviour of a rigid rotor in active magnetic bearings was developed. The model is nonlinear and has five degrees of freedom and can only be solved numerically. The Newmark beta method and the Newton-Raphson method were used to solve the system of nonlinear differential equations. The results of the simulation showed the advantages of using active magnetic bearings for annulling sudden occurrences of unbalance in rotary machines.